The present keyboard keys used for entering data to computers are divided into the vertical elevating type key and the bridge type key, and the bridge type key adopts two cross movable stands to shift the key up and down by compressing the key vertically. Compared with the vertical elevating type key, the overall height of the bridge type key is lower. The reason for the overall height of the vertical elevating type key being higher than that of the bridge type key resides on that the vertical elevating key as shown in FIG. 1 is coupled to the keyboard, and the key comprises a key cap base, a key cap body coupled to the key cap base and displaced vertically on the key cap base, and an electrically conductive cap body disposed on the key cap base for providing a resilient force to the key cap body, and the elevating mode makes use of a pressing pillar being disposed at the central position of the key cap body and compressed onto the electrically conductive cap body to store resilience, or being released to resume the original position of the key cap body by the resilient force from the electrically conductive cap body.
However, when a user enters data from the keys, the user usually does not exert a force at the central position of the key cap body all the time. If the force is exerted on the area of the four corners of the key cap body, the height of the pressing pillar of the key cap body must be substantially equal to the moment at the four corners of the key cap body with respect to the center to assure the force of each stroke is pressed onto the key. The height of the vertical elevating type key depends on the size of the key cap body and cannot be as thin as the bridge type key.